MCKagan was at a launch party for his new book, How to Be a Man at the Neptune, when the odd collaboration took place.

The former GUNS N' ROSES star played bass as his rocker pal accompanied him on accordion.

The odd get together came just days after MCKagan dismissed reports suggesting Sweet Child O' Mine was ripped off from rockers Australian Crawl

The group's singer, James Reyne, recently pointed out that their 1981 track Unpublished Critics bears similarities to the 1987 rock anthem.

But MCKagan told U.S. radio show Opie Radio, "At that point, Guns were trying to be so original and different to do our own thing. There's just no way we would have referenced anything. So if there's any similarity, it's complete happenstance... Any bands I've been in, you do the small check for comparisons."